Operation filter

stream.Filter

It discard those elements in the stream that do not match with the given filter.

Signature

func (s stream.Stream) Filter(fn func(interface{})bool ) (out stream.Stream)

Arguments

Name	Type	Description
fn	func	This function must receive 1 arguments, that must have the same type that current elements in the stream. The output of this function will be a bool, being true if the element matches the filter or false if not

Output

Name	Type	Description
out	stream.Stream	It returns the stream

Errors

Type	Description
err.items-nil	The stream is nil
err.invalid-argument	The filter operation requires a function as argument
err.invalid-argument	The provided function must retrieve 1 argument
err.invalid-argument	The provided function must return 1 value
err.invalid-argument	The type of the argument in the provided function must be the same than the elements in the stream
err.invalid-argument	The type of the output in the provided function must be bool

Example

package main

import (
  "fmt"
  "github.com/wesovilabs/koazee"
)

type Food struct {
  Name    string
  Healthy bool
}

var foodSlice = []*Food{
  {"Vegetables", true},
  {"Nuts", true},
  {"Sweets", false},
}

var stream = koazee.StreamOf(foodSlice)

func main() {
  stream = stream.Filter(func(f *Food) bool {
    return f.Healthy
  }).Do()
  for _, f := range stream.Out().Val().([]*Food) {
    fmt.Println(f.Name)
  }
}

Download

Benchmark

Removing from the stream those elements that they're not even

Test Identifier	Stream Len	Speed
BenchmarkFilterNumbers10LenIsEven-4	10	850 ns/op
BenchmarkFilterNumbers100LenIsEven-4	100	1785 ns/op
BenchmarkFilterNumbers1000LenIsEven-4	1000	17190 ns/op
BenchmarkFilterNumbers5000LenIsEven-4	5000	26437 ns/op